Apparatus for transmitting coded currents



Sept. 2, 1930. L. v. LEWIS APPARATUS FOR TRANSMITTING CODED GURRENTS Filed March 26.. 1929 QB k m Q Q Q 0 aw m; w 3 mm 4 ww mm v LE M m I QR QQLW MN Q N l N N .B\ Q H N All MN I Q m- & W w NW. 1% mm A Q mmj Mg Q IQN w Q 7. RN. Qm w Q Q NN Q N QWN N 5 R NAJTw A||| w w Patented Sept. 2, 1930 marsh srArEs PATENT OFFICE.

LLOYD V. LEWTS, 0F EDGEVIOOD BOROUGH, PENNSYLVANIA, ASSIGNOB TO THE UNION SWITCH SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION OLE PENNSYLVANIA APPARATUS FOR TRANSMITTING CODED CURRENTS Application filed March 26; 1929. Serial No. 350,001.

- My invention relates to apparatus for transmitting periodically interrupted, or coded currents, and is particularly suitable for, though not limited to, supplying the rails of a railway track with periodically interrupted alternating currents which may be used to control trackway signals or train carried governing means or both.

One feature of my invention is the provision of means for selectively controlling the rate and duration of the interruptions by means of relays.

T will describe two forms of apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawings, Fig. '1 is a i ll 1 "tmll1&t1C view showing one form of apr paratus embodying my invention. Fig. 2-is a diagrammatic view showing another form of apparatus also embodying my invention.

Similar reference characters refer to similar parts in both views.

Referring first to Fig. 1, the reference characters 1 and 1 designate the track rails of a stretch of railway track over which traf he moves from west to east, which, as indicated by the arrow, is from left to right, as shown in the drawing. These track rails are divided by means of insulated joints 2 into a plurality of track sections only one of which, section A-B is shown complete in the drawing. A track relay, designated by the reference character T with a distinguishing suiiix, is connected across the rails adjacent one end of each of these sections and may be used to control other traffic governing apparatus, not shown in the drawing, in

any desired manner. Current for operating each relay T is supplied to the respective section by a track battery 3 connected in series with a secondary winding 13 of a transformer F across the rails adjacent the opposite end of the section.

Traflic control relays, designated by the reference letter H with distinguishing suffixes, are controlled by the track relays of two adjoining sections. A back contact 22 of each track relay T controls an approach relay P.

Alternating current is at times supplied to section AB by secondary Winding 13 of transformer F. This alternating current is coded, or periodically interrupted, at one of three prescribed rates according to traliic conditions. The rate of interruption is determined by threegroups of relays, the first and E For controlling current of each ofthe three codes, the relaysof each of these groups, respectively, are operated in cascade, that is, they are separately, and 1n turn, re-

peatedly energized and de-energized.

Normally, section AB being unoccupied, track relay T is energized, and all the code control relays are de-energized. Upon relay T becoming de-energized by the entrance of a train into section AB, approach relay P becomes energized and closes its contact 27.

If relays H and T are both energized, the first group of relays C and C will be operated; if relay T is energized but relay H is de-energized, the second group of relays C C D and D will be operated; and if both relays T and H are de-energized, the third group of relays C C D D E and E will be operated.

Assuming that contact 27 of relay P is closed and that relay C is energized, then when relay C becomes de-energized, the relay magnet M becomes energized, attracting an armature a which swings about a hinged end 19 and to the opposite end of which a spring I) is attached. The end 20 of spring I) is fixed. Armature a, upon being attracted by magnet M, moves away from a fixed stop 21, stretching spring 6. A tuned reed or vibrator 57, rigidly connected at one end to armature a and free to vibrate at its opposite end so as to close alternately contacts 58 and 59, moves with armature a. Contacts 58 and 59 are mounted on armature a on opposite sides of reed 57, and therefore also move with armature a.

When relay C becomes energized, magnet M is de-energized and hence springv I) retracts armature a sharply against stop 21, setting reed 57 into vibration to alternately and repeatedly close contacts 58 and 59.- Reed 57 is arranged to vibrate freely with small damping, so that its vibrations will continue for a time at least equal to the time that relay C is energized. Contacts 58 and 59 are connected with end terminals 17 and 16, respectively, of the primary winding of trans former F. A midpoint 18 of this primary winding is connected through wire 0 with the negative terminal of a battery L When reed 57 is vibrating while relays P andC are energized, the positive terminal of a battery L is connected with terminals 16 and 17, alternately, of the primary winding of transformer F through contacts 59 and 58, respectively, causing alternating current to be supplied to rails 1 and l by secondary winding 13 of transformer F. Sparking at contacts 59 and 58 is prevented by means of a secondary winding 14 of transformer F, whose terminals are connected to a condenser 15.

A heat responsive relay G comprises a heater 86 connected in with reed and a thermostatic contact 63 which controls the pickup circuit for a stick relay R The closing of contact 68 occurs only after relay G has been energized for a considerable period of time, such as in the event of long continued de-energization of relay T by a train having stopped in section AB. Ts hen contact 3 closes as the result of a rise in temperature of heater 86, relay R becomes energized, opening the circuit for relay P which in turn opens its contact 2? thus dis ontinuing the operation of the code control relays.

An asymmetric unit a, is so connected in multiple with the winding of each code control relay that the high resistance direction of the asymmetric unit is opposed to the flow of current from the source which energizes the respective relay. Each asymmetric unit 4 may be similar to those disclosed and claimed in Letters Patent of the United States, No. 1,6st0.335, granted to L. O. Grondahl, August 23, 1927. By means of these asymmetric units connected in multiple with the windings of the code relays, the code relays are caused to be slow releasing.

In Q, the track circuits are supplied. with current from the secondary winding 73 of a track transformer Q through the usual innaedance device 74-. Vi hen relay P is deenergized, the primary winding 72 of trans former Q is continuously supplied with alternating curren by a source X over wires and Upon the energization of relay l causing e de relay C to be operated, winding 82' of a polarized relay N becomes energizer, attracting armature 84- which completes the circuit for the primary winding of transformer Q, through frontcontact ot relay P. Upon the subsequent de-energization of relay C this circuit for the primary winding 01' transfer-inert} is opened because winding 81 of relay N then opens contact 84.

Having thus described in general the arrangement and location of the various parts comprising my invention, 1 will now describe the operation of the apparatus.

As shown in the drawing, all parts are in their normal condition, that is, section Al5 and the first and second sections in advance of section A-B are unoccupied. Track relays T and T and traffic control relays H and H are therefore energized. The circuit by which relay H? is energized passes from battery L through wires 5 and 6, contact 7 of relay T wire 8, contact 9 of relay 1", wire 10, winding of relay H and wires 11 and 12 back to battery L Relay H is energized by a similar circuit including contact 9 of relay T and atront contact of the track relay for the second section, in advance of section AB.

I will now assume that an eastbound train tie-energizes relay T which then completes at its back contact 22, the pick-up circuit for relay P passing from a battery L through contact 22, wire 23, contact 24 of relay ll, winding of relay P, and wires 25, 12, and 26, back to battery L Relay P thereupon closes its contact 27, completing a pick-up circuit for relay C passing from battery L through wire contact 27 of relay P, contact 28 of relay T contact 29 of relay H wire 30, contact 31 of relay C wire 32, the winding of relay C and wire 0 back to battery L Relay C upon becoming energized, closes its Contact 34:, thereby completii'ig the pickup circuit for relay 0 which passes from battery L through wire 5, contact 27 of relay P, wire 33, contact 3st of relay C wire and the winding of relay C to wire 0. Relay 0 upon becoming energized, opens its contact 31 thus breaking the pick-up circuit for relay C The current {lowing in relay C therefore discharges through asymmetric unit 4-, and after short interval, the front contacts of relay C open and its back contact closes, completing the picieup circuit for magnet M passing from battery L through wire 5, conta t 27, wire 33, contact 55" of relay C and the winding of magnet M to wire 0. Magnet M therefore picks up armature (I which carries the vibrator 57 and con tacts 58 and 59. Spring 20 is thereby put under tension.

Vv'hen contact 3-1 of relay C opens, it breaks the pick-up circuit for relay he current flowing in relay C therefore discharges th rough asymn'ietric unit 4 connected acr its terminals and after a short interval, relay C permits its contact 31 to close. Relay C then being energized by its pick-up circuit alre' ly traced, opens contact 55" a d closes its contacts 3% and Contact thus Lie-energizes magnet M which then releases its armature a. Spring Z thereupon retracts armature a until it is arn by stop 21, and thereby sets the tuned reed 57 in vibration.

A circuit now passes from battery L through wire 5, contact 27 of relay P, wire 33, contact 55 of relay C wire 56, heater 86 of relay G, to reed 57. Reed 57, when vibrating, connects alternately with contacts 59 and W hen reed 57 connects with cont-act 59, the circuit is completed through wire 60, terminal 16, right-hand primary coil of transformer F, and terminal 18 to wire 0.

W'hen reed 57 connects withcontact 58, the circuit is completed through wire 61, terminal 17, left-hand primary winding of transformer F, and terminal 18 to wire 0. Battery current is thus supplied alternately to the two end terminals of transformer F,

causing alternating current to be del vered to the rails 1 and 1 by secondary winding 13 of transformer F, The frequency of this alternating current is determined by the rate of vibration of tuned reed 5. and in practice is preferably 100 cycles per second.

With contact 34 of relay C closed, relay C is energized, by its circuit previously traced, and hence opens, at its contact 31, the circuit for relay C When contact55 of relay C opens, it breaks the circuit to reed 57, and contact 55 of relay C then closes the circuit for magnet M. The generation of alternating current is thus discontinued. The opening of contact 34 01 relay C breaks the circuit for relay C l Vhen contact 31 of relay C then closes, it completes the circuit previously traced for relay C and the cycle of operation just described is then repeated It followsthat, as long as relays l and H are energized, relays C and C will be repeatedly energized and ole-energized, that alternating current will be supplied to the track rails duringthe intervals 'iueasured by the sum of the pick-up time of relay C and the release time of relay C and that the alternating current will be discontinuedduring the intervals measured by the sumfot the release time of relay C and the pick-up time of relay C I It now the train passes out of section A-B, current from battery 3 will again be supplied to track relay T which will then open its contact 22 and so deenergiz'e relay P and thus stop the generation of alternating current.

I will now assume that the section to the right of location B is occupied so that relays T and H are deenergized. It, now, an east-- bound train enters section A-l3, relay T will become de-energized and relay Pwill then become energized and energize magnet M. In this case, operationof the third group of code control relays is begun by a circuit passing from battery L, through wire 5, contact 27 of relay P, contact of relay T wire 46, contact 47 of relay E wire 48, and

the winding of relay E to wire 0. itelay E is thus energized, and thereupon closesits contact 50 which completes a pick-up circuit for relay D passing from batteryL through wire 5,contact 27 of relay P, wires 33, 39 and 49, contact 50 of relay E wire 38, and the winding of relay D to wire 0. Relay D thereupon closes its front contact 40, completing a picloup circuit for relay C passing from battery L through wire 5, contact 270i relay P, wires 33 and 39, contact 40, wires 41 and 32, and the winding of relay C to wire 0. Relay C therefore becomes energized and opens its back contact 55, de-energizin magnet M, and closes its front contact 55, causing alternating current to again be supplied by secondary winding 13 of transformer F to rails 1 and 1 Relay C upon becoming energized, closes its contact 34, causing relay C to become energized as previously described. Relay C thereupon completes a pick-up circuit for relay D passing from battery L through wire 5, contact'27 of relay P, wires 33'and 39, contact 42 of relay 1), wire 44, contact 45 of relay C ,and the wind in g of relay D to wire 0. Relay D thereupon closes its contact 54, completing a pick-up circuit for relay E passing from battery L through wire contact 27 of relay P, wires 33, 39 and 49, contact 51 of relay E wire 53, contact 54 of relay D and the winding of relay E to wire 0.

Relay E then opens its back contact 47, thus breaking the pick-up circuit for relay E which is thereby de-energized. Although contact 51 of relay E now opens, relay E continues energized by a stick circuit which includes the path already traced for its pickup circuitas far as wire 49, thence through contact 52 of relay E wire 53, contact 54 of relay D and the winding of relay E to wire 0. Relay E upon becoming de-energised, also opens its contact 50, causing relay D "to become de-cnergized Relay D upon becoming deenergized, opens its contact 42 n the pick-up circuit for relay D which, however, continues energized by a stick circuit which follows the path already traced for its pick-up circuit as far as wire 39, thence through contact 43 of relay D wire 44, contact of relay C and the winding of relay D to wire 0. Relay D upon becoming deenergized, also opens its contact 40, causing relay C to become de-energized and opens its contact 55 which interrupts the supply of alternating current from secondary winding '13 of transform-er F. Contact 55 of relay C then closes, causing magnet M to again be energized. Contact 34 of relay C also opens and de-cnergizes relay C Contact 44 of relay C when it opens,breaks the stick circuit for relay D which then becomes deenergized. Relay 1) thereupon opens its contact 54 in the stick circuit for relay E causing relay E to become de-energized. Relay E upon becoming de-energized, closes its contact 47, causing energy to again be suppliedto relay E and thus start a second operating cycle of the relays of the third group.

It follows, therefore, that as long as relay P is ener ized and relays T and H are deenergized, relays C C D D E and IE will be repeatedly energized and de-energized, and that alternating current will be supplied to the track rails during the intervals measired by the sum of the pick-up times of relays C D and E and of the releasetimes of relays E 1) and C and will be discontinued during the intervals measured by the sum of the release times of relays C D and E and the pick-up times of relays E D and G I will now assume that the first section to the right of location B is unoccupied, but that the second section to the right of location B is occupied, so that relay T is energized but relay H is de-energized. It, now, an eastbound train enters section AB, de-energizing relay T and thus energizing relay P, the operation of the second group of relays is begun by a circuit passing from battery L over wire 5, contact 27 of relay P, contact 28 of relay T contact 29 of relay H wire 36, contact 37 of relay D wire 38, and the winding of relay D to wire 0. Relay D becoming energized, completes the second pick-up circuit previously traced for relay C causing relay C to become energized. Relay C upon becoming energized, opens its back contact 55", thus breaking the circuit for magnet M which has previously been energized. upon the closing or" contact 27 of relay P. Armature a is then released by magnet M, and, upon the closing of contact 55 of relay C transformer F is caused to supply alternating current to rails 1 and 1 as already described. Relay C upon becoming energized, also closes its contact 34 thus causing energization of relay C Relay C upon becoming energized, completes the pick-up cir' cuit for relay D as already traced through contact of relay C Relay D then opens its contact 37, causing relay D to become tie-energized. Although contact 42 of relay D is now open, relay D continues energized by its stick circuit previ ously traced. Relay D by opening its contact d0, causes relay C to be Clo-energized and thus interrupt, at its contact the circuit for causing the supply of alternating current by transformer F to the track rails. Relay C also opens its contact 34, causing relay C to again be de-energized and in turn deenergize relay D by the opening of contact 45. Relay D upon becoming (lo-energized, closes its contact 37, thus again completing the second pick-up circuit for relay D and starting a second operating cycle of the relays in the second group.

It follows, therefore, that as long as relays P and T are energized and relay H is deenergized, relays C C D and D will be repeatedly energized and de-energized, and that alternating current will be supplied to the track rails during the intervals measured by the sum of the pick-up times of relays C and D and the release times of relays D and C and will be discontinued during the intervals measured by the sum of the release times of relays C and D and the pickup times of relays D and G I will now assume that, when all parts of the apparatus are again in their normal condition, as previously described, a train enters and stops in section A-B. If the train remains long enough in section A-B, the repeated energization of the winding of heat responsive relay G, by current flowing through it to the primary winding of trans former I will cause relay G to close its contact 63. Stick relay R will then be energized by its pick-up circuit passing from battery L through wire 62, contact 63 of relay G, wire 64, winding of relay R, and wire back to battery L Relay R, upon becoming energized, opens, at its contact 248, the circuit for relay P which then opens its contact 27, interrupting the flow of current from battery L to the code control relays and to transformer F. Relay R, as long as the train subsequently remains in section AB, continues energized by its stick circuit which passes from battery L through contact 22 of relay T wire 23, contact 25% of relay R, winding of relay R, and wires 25, 12 and 26 baci: to battery L The code control relays will not again become energized until relay T has become energized and has de-energized relay R, and has then become de-energized and has energized relay I Each of the relays in the three groups referred to may have any desired characteristies. In further discussing the operation of these groups, I will assume a time unit of 1/ th of a second. I will next assume that, as an example, each of the relays has a pickup time of one of these units, that relays C and C when operated in multiple, with asymmetric units 4 in the circuits of Fig. 1, have a release time of 9 units, that relays D and D in the circuits shown have a release time of 4 units, and that relays E and E in the circuits shown have a release time of 6 units.

In the operation of the first group, the pick-up and release values of relays C and C being as thus assumed, relay C picks up in one unit of time after the application of energy to its winding. Relay C then picks up after the lapse of a second unit of time. Relay G now being de-energized by the opening of contact 31 of relay C opens its front contacts after a lapse of 9 units of time. Relay C then being ole-energized, closes its back contact after the lapse of a second period of 9 units thus putting the circuit for relay C in condition for the beginning of a second cycle of operation. It is thus clear that the first cycle of operation ill consumes a total period of time including the pick-up periods and the release periods of both relays C and C summing up to 20 units, and that alternating current is supplied to the track for 10 units, and is out OK for 10 units. Each succeeding operating cycle of this first group of relays requires a like period of 20 units oftime. In the operation of the relays in the second group, the total time required for each cycle consists of the pickup periods of four relays and the release periods of these four relays, resulting in a totalperiod of-80 units, and alternating current is supplied to the track for 15 units, and is out oft for 15 units. Similarly, the total time for each cycle of operation of the relays in the third group is 45 units, during 22 of which alternating current is supplied to the track, and during 22 of which alternating. current is discontinued,

It is therefore clear that,'for a complete operating cycle of the first, second or third groups of relays, the time required is respectively A and A of a second. The first group therefore has an operating frequency of three cycles per second, the second group has an operating frequency of two cycles per second, and the third group has an operating frequency of 1 cycles per second. It is clear that, by controlling magnet M and transformer F by contacts of relay C alter; natingcurrent, interrupted three times per second, is supplied by transformer F to rails 1 and l when the first group of relays is operated; alternating current, interrupted twice per second, is supplied to rails -l and l when the second group of relays is operated and alternating current, interrupted one and one-third times per second is supplied to rails 1 snar when the third group of relays is operated. 1

With the arrangement shown in Fig. 2, the three groups of relays are assumed'to operate in cascade similarly to the manner described in connection with Fig. 1. In Fig. 2, alternating current is supplied by a source X instead of by the arrangement including battery L magnet-.M and transformer 1*" shown in Fig. 1. NVith relay P de-energized,

rails 1 and l, as shown in F ig. 2, are supplied with alternating current by secondary winding 73 ofitransformer Q by means of .a circuit passing froml source K, through wires 65and 69, contact of'relay P, wire 71, primary winding 72 of'relay Q, and wires 67 andi68 back to source X. As in Fig. 1, so, in Fig. 2, relay P becomes ener gizedwhen" relay 1T becomes dc-energized, the circuit for relay P in Fig. 2 passing from source X, through wire 65, c0ntact 66 of relay T winding of relay P, and wires 67 and 68 back to source When relay. P becomes energized, winding 81 of relay N'becomes energizedby its circuit passing from battery L through contact 76 of relay P, wire 77,,contact 55? of relay C wire 80, and winding 81- towire 0. Each timev relay C becomesenergized during a cycle of operation of anyone of the three groups of relays while relay P is energized, winding 82 of polarized relay N becomes energized by a circuit passing from battery L through contact 76 of relay P, Wire 77, contact 55 of relay 6, wire 7 9, and winding 82'to wire 0.- VVinding-SQ, becoming energized, causes contact-.84 to close, 7

and current is nowsupplied to primary winding 7 2 of transformer Q by a circuit passing from source X, through wires 65 and 83, contact Set of relay N, wire 85, contact 70 of relay P, wire 71, primary winding 72,and wires 67 and 68 back to source Upon the subsequent de-energization of relay while relay P is energized, winding-82 becomes deenergized and winding 81 againbecomes energized, opening contact 8 1 and breaking the circuit through primary winding 72 of transformer Q. I I

The supply of current to primary winding 72 is thus interrupted every time relay C becomes de-energized whilerelay P is energized. It is therefore clear that, while the first group of relays is operating, the alternating current being supplied to primary winding 72 of transformer Q, is interrupted threetimes every second; while the second group of relays is operating, the currentsupplied to primary winding 72 is interrupted twice per second; and while the third group of relays is operating, the current supplied to primary Winding 72 is interrupted one and one-third times per second. i i Although I have, for purposes of illustration, assumed definite values for the pickup and release periods of the relays in each of the three code control groups, it should be pointed out that my invention is not limit ed to these particular values.

Although I have herein shown and .de-

scribed only two forms of coded, current transmitting apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope ofthe appended claims without departing from the spirit and scope of'my invention. .Having thus described my invention, what I claim is: I

1. In combination with a conductor, a plurality of. inter-inclusive groups of relays, means for operating'in-cascade the relays in each of said groups, a source-of current, and means including saidsource andcontrolled by a contact of a relay of each of said groups for supplying a plurality of coded currents to said conductor. i A

:2. In combination with a conductor, a plurality of groups of relays, a coderelay included in all ofsaid groups, meansfor operating in cascade the relays. in each ofsaid groups, a source of current, and means including said source and controlled by a contact of said code relay for supplying a plurality of coded currents to said conductor.

3. In combination with a conductor, a plurality of groups of relays, certain relays of each of said groups included in each of the other said groups, means for operating in cascade the relays in each of said groups, a source of current, and means including said source and controlled by a contact of a relay'of each of said groups for supplying a plurality of coded currents to said conductor.

4. In combination with a conductor, a plurality of groups of relays, certain relays of each of said groups included in certain of the other said groups, means for operating in cascade the relays in each of said groups, a source of current, and means including said source and controlled by a contact of a relay of each of said groups for supplying a plurality of coded currents to said conductor.

5. In combination with a conductor, series of groups of relays, the first group in said series including a plurality of relays, the second group in said series including the relays of said first group and additional relays, similarly each succeeding group in said series including the relays of the next preceding group and additional relays, means for operating in cascade the relays in each of said groups, a source of current, and means including said source and controlled by a contact of a relay of each of said groups for supplying a plurality of coded currents to said conductor.

6. In combination with a conductor, a plurality of inter-inclusive groups of relays, means for operating in cascade the relays in each of said groups, a sourceof current, and means including said source and controlled by a contact of a relay of each of said groups for supplying a respective coded current to said conductor.

7. In combination with a conductor, a plurality of inter-inclusive groups of relays, means for operating in cascade the relays in each of said groups, a source of current, a

code relay controlled by said groups, and means including said source and controlled by a contact of said code relay for supplying a plurality of coded currents to said eonductor.

8. In combination with a conductor, a plurality of inter-inclusive groups of relays, means for repeatedly energizing and deenergizing in cascade the relays in each of said groups, a source of current, and means including said source and controlled by said relays for supplying a plurality of coded currents to said conductor.

9. In combination with a conductor, a plurality of inter-inclusive groups of relays, means for operating in cascade the relays ineach of said groups, a source of current, and

means including said source and controlled by each of said relay groups for supplying said conductor with a coded current of a different characteristic from the coded current which is controlled by each of the other said groups.

10. In combination with a conductor, a series of grou is of relays, the first group in said series comprising a pair ofrelays the first of which has a pick-up circuit controlled by a back contact of the second, and the second of which has a pick-up circuit controlled by a front contact of the first, the second group in said series comprising a third and a fourth relay as well as the relays of said first group, a pick-up circuit for said fourth relay controlled by a back contact of said third relay, a second pick-up circuit for said first relay controlled by afront contact of said fourth relay, a pick-up circuit for said third relay controlled by front contacts of said second and fourth relays, a stick circuit for said third relay controlled by a front contact of said second relay, each succeeding group in said series comprising the next preceding group and two additional relays, the sem 1d of said additional relays having a pick-up circuit controlled by a back contact of tie first said additional relay, a front contact of said second additional relay controlling a second pick-up circuit for the second additional relay of the next preceding group, the said first additional relay having a pickup circuit controlled by front contacts of the accompanying said second additional relay and of the first additional relay of the next preceding group, each said first additional relay having a stick circuit controlled by a front contact of the first additional relay of the next preceding group, means for causing the operation of each of said groups separately from each of the other said groups, a source of current, and means including said source for supplying said conductor with current of one code or another according as one or another of said groups of relays is operating.

11. In combination with a conductor, a plurality of inter-inclusive groups of relays, means for operating in cascade the relays in each. of said groups, an asymmetric unit connected in multiple with the winding of each of said relays, a source of current, and means including said source and controlled by said relay groups for supplying a plurality of coded currents to said conductor.

12. In combination with a conductor, a series of relays operating in cascade, an asymmetric unit connected in multiple with the winding of one of said relays, a. source of current, and means including said source and controlled by said relays for supplying codedcurrent to said conductor.

13. In combination with a conductor, a plurality of inter-inclusive groups of relays,

means for operating in cascade the relays in each of said groups, a source of current, and means including said-source and controlled by said groups of relays for supplying a plurality of coded currents to said conductor.

14:. In combination With a conductor, a plurality oi inter-inclusive groups of relays, means for operating in cascade the relays in each of said groups, a source of current, and means including said source and controlled by said relay groups for at difiierent times supplying said conductor With current of difl'erent codes.

15. In combination With a conductor, a

stretch of railway track, a plurality of interinclusive groups of relays, means for operating in cascade one or another of said groups of relays according to trafiic conditions Within said stretch, a source of current, and means including said source and controlled by said groups of relays for supplying a plurality of coded currents to said conductor.

16. In combination, a stretch of railway track over which traflic moves in one direction, a plurality of inter-inclusive groups of relays, means for operating in cascade one or another of said groups of relays according to traflic conditions in forward sections of said groups of relays for supplying a plurality of coded currents to a rear section of said stretch.

In testimony whereof I afiix my signature.

LLOYD V. LEWIS.

stretch, a source of current, and means n including sald source and cont-rolled by said 

